Preliminary proton nmr studies on the 5' -guanosine monophosophate dianion (5' -GMP) have shown that the spontaneous self-assembly of the mononucleotide in homogeneous aqueous solution (pH equals 7.0-8.5) depends dramatically on the nature of the alkali metal counter-cation. The Na ion, K ion and Rb ion salts of the 5' isomer all form regular ordered structures, whereas the Li ion and Cs ion salts fail to form self-structures under analogous conditions. The results demonstrate for the first time that alkali metal ions can play a principal structure-directing role in the solution ordering of a nucleic acid through a size-selective complexation mechanism. The related guanine nucleotides 3', 5'-cGMP, 5'-dGMP, 5'-GDP, and 5'-GTP, among others, should also form self-structures in homogeneous solution and should exhibit alkali metal ion selectivity. The proposed research will elucidate the structural consequences of this new alkali metal ion coordination chemistry of guanine nucleotides. The chief general objectives will be to assign specific structures to the various ordered forms by performing detailed multinuclear nmr studies and variable temperature infrared studies on the parent nucleotides and their structurally relevant derivatives. The results should provide insight into the mechanisms of certain biological functions of guanine nucleotides. Some of the anticipated self-structures will be examined for their potential utility in binding planar drug molecules and metalloporphyrins capable of reversible oxygen binding.